Field of the Invention
This application is in the field of solids flow and processing and more specifically relates to an improvement for use in solids blenders. Typically, such a blender includes a cone-shaped hopper from which a cylindrical bin extends upwardly. Typically, a feeder valve and a conveyor are located at the bottom of the hopper.
Graular solids flowing in a cylindrical column have a natural tendency to produce a uniform velocity in the upper reaches of the cylindrical column even when a large velocity gradient is imposed at the bottom of the cylindrical column by a hopper.
This tendency for a uniform velocity profile is greater when the effective angle of internal friction is small (less than 35.degree.).
For a successful gravity flow blender, one wants to produce a smooth non-uniform velocity profile and to propagate this gradient throughout the blender. Since the natural tendency of flowing solids is to form uniform velocity profiles in cylindrical bins, the useful height of these bins is generally limited to one or two bin diameters of height in the cylinder.
Some improvement may be obtained by using a cone-in-cone hopper blender of the type described in U.S. Pat. No. 4,286,883 of the present inventor. But even this type of apparatus may not propagate a significantly non-uniform velocity profile more than about one diameter vertically.
The present invention allows the useful height of these cylindrical bins to extend upward to several bin diameters by propagating the desirable velocity profile throughout the entire length of the cylinder.